Use of cavity ring-down spectrometry to quantify 13 C-primary productivity in oligotrophic waters
AuthorsLópez-Sandoval, Daffne C.
Duarte, Carlos M.
KAUST DepartmentBiological and Environmental Sciences and Engineering (BESE) Division
Marine Science Program
Red Sea Research Center (RSRC)
Online Publication Date2019-01-14
Print Publication Date2019-02
Permanent link to this recordhttp://hdl.handle.net/10754/630926
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AbstractCavity ring-down spectroscopy (CRDS) is a highly sensitive laser technique that allows the analysis of isotopic signals and absolute concentration of individual molecular species in small-volume samples. Here, we describe a protocol to quantify photosynthetic 13C-uptake rates of marine phytoplankton by using the CRDS technique (13C-CRDS-PP). We validated our method by comparing the 13C-PP rates measured between CRDS and isotope ratio mass spectrometry (IRMS) in samples with different carbon content (30–160 μgC). The comparison revealed that 13C-CRDS-PP rates were highly correlated with those obtained by IRMS (Spearman correlation coefficient, ρ = 0.95, p < 0.0001, n = 15), with a mean difference between the two estimates of ± 0.08 mgC m−3 h−1. Moreover, the slope of the relationship between CRDS and IRMS results was not significantly different from 1 (F = 0.03, p = 0.86), and the intercept did not differ from 0 (F = 1.4, p = 0.24), indicating that there was no bias in the CRDS relative to the IRMS-based measurements. A separate analysis also showed that despite the difference in volume and carbon content between samples (40 ± 10 μgC and 160 ± 40 μgC, respectively), the 13C-CRDS-PP technique provides similar results (Mann–Whitney test, U = 30.5, p = 0.90, n = 8). In addition, 13C-CRDS-PP rates measured along the Red Sea (∼ 176 mgC m−2 d−1) agreed with 14C-based PP rates previously reported for similar locations. Thus, this study evidenced that the 13C-CRDS-PP method is sensitive enough to quantify carbon fixation rates in oligotrophic regions.
CitationLópez-Sandoval DC, Delgado-Huertas A, Carrillo-de-Albornoz P, Duarte CM, Agustí S (2019) Use of cavity ring-down spectrometry to quantify 13 C-primary productivity in oligotrophic waters. Limnology and Oceanography: Methods. Available: http://dx.doi.org/10.1002/lom3.10305.
SponsorsThe research reported in this publication was supported by funding from King Abdullah University of Science and Technology (KAUST), under award number BAS/1/1071-01-10 assigned to CMD, BAS/1/1072-01-01 assigned to SA, and FCC/1/1973-21-01 assigned to the Red Sea Research Center. We also thank to the anonymous referees for their helpful and valuable comments and suggestions to improve our manuscript.
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